It has become well known in the surgical arts to utilize various organic (autologous and homologous) and synthetic surgical devices at a surgical site to reinforce or augment the tissues being repaired or otherwise modified. These surgical devices include many distinct structures, including but not limited to surgical meshes, plates, screws, sutures, heart valves, bulking compounds, breast implants, and replacement joints. These devices may be fashioned from many different organic and inorganic materials.
While the functions of the aforementioned surgical devices are varied, the immunostimulating coating of the present invention acts in the same manner regardless of the type of surgical device to which it is applied. The need for a coating such as that of the present invention and the method in which it functions is generally described herein below and with more specificity as the present invention applies to a surgical mesh.
Surgical meshes are porous, gauze-like sheet materials which may be woven or spun from a variety of organic and synthetic materials. Common uses of surgical meshes include the repair of herniations and use as a structural member in gynecological surgeries. The materials from which surgical meshes are made must be biocompatible, chemically and physically inert, non-carcinogenic, mechanically strong, and easily fabricated and sterilized. Most synthetic surgical meshes are woven from monofilament or multifilament fibers to form a mesh having pores of varying sizes and geometries. Other synthetic surgical meshes are formed in a node and fibril arrangement in which the mesh is comprised of larger sections or nodes which are interconnected by fibrils of the mesh material. A non-exhaustive list of common surgical meshes is given in Table 1 below.
TABLE 1ChemicalComponentTrade NameTypePorespolypropyleneMarlex (CR Bard, Cranston, RI)Mono-IrregularfilamentProleneMono-Diamond(Ethicon, Somerville, NJ)filamentAtriumMono-Irregular(Atrium Medical, Hudson, NH)filamentpolytetra-Teflon (CR Bard, Haverill, MA)Multi-CircularfluoroethylenefilamentPTFEexpandedGore-texMulti-Node andPTFE(WL Gore, Flagstaff, AZ)filamentFibrilMacroporepolyethyleneMersileneMulti-Hexagonalterephthalate(Ethicon, Somervill, NJ)filamentpolyglycolicDexon (absorbable)Multi-Diamondacid(Davis + Geck,filamentAmerican Cyanamid,Danbury, CT)Polyglactin 910Vicryl (absorbable)Multi-Diamond(Ethicon, Somerville, NJ)filament
Organic surgical meshes are typically derived from human or animal sources. Homologous surgical meshes may be derived from the tissues of a donor, from animal tissues, or from cadaveric tissues. Autologous surgical meshes are meshes that are derived from a patient's own body, and may comprise dermagraphs, fascia tissues, and dura mater.
The most common use of surgical meshes involves the reinforcement of herniations. Surgical meshes are also used in gynecological procedures including abdominal sacrocolopopexy and as suburethral slings. Other procedures which require surgical meshes include laparosopic retropubic urethropexy, intraperitoneal placement for adhesion prevention, the repair of pelvic floor hernias, rectoceles, and cystoceles. It is to be understood that the aforementioned surgical procedures do not comprise a complete list of all uses of organic and synthetic surgical meshes. New and varied uses for surgical meshes, and for all surgical devices, are being discovered on an ongoing basis and the present invention is to be construed to be applicable to all present and future uses of surgical devices such as a surgical mesh.
In many surgical procedures, it is desirable that a surgical mesh become incorporated into the tissues surrounding a surgical site. One example of such a surgical procedure is the reinforcement and repair of a herniation. In the repair of a hernia, and after the hernia has itself been closed using standard surgical techniques, a surgical mesh of appropriate size and shape is placed over the newly repaired hernia and secured in place using sutures, staples, surgical adhesives, or any other suitable connecting means. As the tissues surrounding the surgical site heal, granulation tissues growing at and around the surgical site begin to produce an extracellular matrix which, in a process called fibrosis, infiltrates and attaches to the material of the surgical mesh secured over the surgical site. Incorporation of the surgical mesh into the surgical site by the extracellular matrix strengthens the tissues at the surgical site and helps prevent re-injury.
The rate of recovery of a patient who has undergone a surgery utilizing a surgical mesh is strongly related to the rate at which the surgical mesh is incorporated into the tissues surrounding the surgical site. The rate of incorporation of the surgical mesh as well as the potential for infection and the potential for clinical complications is in turn related to the physical properties of the surgical mesh used. For example, synthetic meshes having pores or interstices of less than 10 μm in size may theoretically promote infection in that small bacteria (less than 1 μm in size) may enter the surgical site through the mesh, while important and larger macrophages and polymorphonuclear leukocytes are prevented from passing through the mesh to the surgical site. In addition, the number, size, and shape of the pores play an important role in tissue bonding to the surgical mesh. Generally, surgical meshes having larger pore sizes are difficult for fibroblasts to adhere to. Furthermore, if a surgical mesh is too stiff, it may cause continuing mechanical injury to the tissues surrounding the surgical site with which it comes into contact. In these cases, a prolonged inflammatory reaction may significantly increase patient recovery time and may also cause clinical complications such as mesh extrusion and enteric fistulas.